The current approach used to construct space based phased arrays is to first design a large planar structural member, possibly of a honeycomb material. Thousands of various components including bandpass filters, radio frequency (RF) electronics modules and control circuits are then tested. If acceptable, the components are mounted onto this structural member. Typically, connections between electrical components are made using coaxial cables. This conventional approach to phased array construction, while straight forward, is highly labor intensive and expensive.
With respect to RF filters, these filters could be any coaxial or waveguide bandpass or bandstop filters. Such filters are often metallic structures having cavities and curves of a predetermined shape and are conventionally secured together by dip brazing or by screw type metal fasteners.
The prior art for the assembling of RF filters is to use metallic screws which act as fasteners keeping a lid in contact with filter cavities. This assembly method is a cumbersome, time consuming and costly involving fine machining and polishing of contact surfaces for a much desired highly conductive seal. Further, the use of numerous screws as fasteners for each filter adds unnecessary weight to the overall structure of a phased array.
Commercial adhesives which are electrically conductive are known. However, their electrical conductivity has much to be desired. The quality and quantity of the metallic filler materials in the adhesives has been found to be low. Also, these commercial adhesives have relatively high electrical losses.
One example is found in U.S. Pat. No. 5,180,523. This patent discloses an electrically conductive cement adhesive filled with silver. The cement adhesive is not described as being for space applications. Further, the cement adhesive has a high shrinkage due to its epoxy resin and also has outgassing characteristics. The outgassing of organic gases into the space environment is unsafe and prohibitive.
The present invention is intended to overcome the above recited shortcomings of conventional space based phased arrays. Also, the present invention may utilize an electrically conductive adhesive cement which improves upon certain characteristics of previous electrically conductive adhesive cements.